thanks scott, i made the change and am reposting, your message, i did a
reply and forgot to see who it was being sent to, you must have your reply
to set in the mail, i leave mine blank.

here is an idea (not tested) 12 bytes of code no looping, and leaves x
alone.

michael

    swapf    x,w
    xorwf    x,w        ; xor nibbles, now we have only 4 bits to test
    andlw    0F0h    ; clear lower nibble for counter
    movwf    parity
    btfsc    parity,4    ; test bits now
    incf    parity,f
    btfsc    parity,5
    incf    parity,f
    btfsc    parity,6
    incf    parity,f
    btfsc    parity,7
    incf    parity,f

    btfsc    parity,0    ; use this to test for parity

-----Original Message-----
From: Scott Dattalo <sdattalo@unix.sri.com>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Friday, March 13, 1998 7:19 PM
Subject: Parity Challenge


>It's been a while since there's been a challenge. And since there's
>been a bunch talk about RS232 stuff, I thought it might be appropriate
>if we had a really fast parity generator for those software bit-banging
>UARTs.
>
>So here's the challenge:
>Given the variable X, write a routine that computes the odd-parity
>of X.
>
>Here's a routine that's slow/looped:
>
>        CLRF    parity
>LOOP:
>        CLRC
>        RRF     X,F             ;Get LSB and put it in the carry
>        SKPNC                   ;If LSB (i.e. C) is set
>          INCF  parity,F        ;then count it
>        MOVF    X,F
>        SKPZ
>          GOTO    LOOP
>
>The least significant bit of 'parity' contains the parity of X.
>
>The best I could do executes in 7 cycles and trashes X.
>
>Scott
>